Electromagnetic smuttle stopping device



June 25, 1940. B. w. JONES 2,205,900

ELECTROMAGNETIC SHUTTLE STOPPING DEVICE Filed Sept. '7, 1938 lnvenfior-zBenjamin W Jones,

His Attorney.

Patented June 25, 1940 PATENT OFFICE ELECTROMAGNETIC SHUTTLE STOPPINGDEVICE Jones, Schenectady, N. Y., assignor to General Electric Compan acorporation of New York Application September 7, 1938, Serial No.228,742

8 Claims.

This invention relates to power drivenlooms.

has been stopped in the shuttle box to accelerate it for the return passin the'reverse direction.

The output of looms utilizing means of this character for acceleratingand stopping the 1f shuttle is limited to a rather definite value. Theuse of the shuttle box for stopping the shuttle at theend. of the passinterferes with the use of more eifective meansfor accelerating theshuttle to a higher speed than is obtainable at the prescut time by theuse of picker sticks.

Accordingly, a further object of this invention is the provision of animproved means for stopping the shuttle that will make it possible toreplace the picker sticks withimproved accelerating means thereby to'increase the weaving speed and the output of the loom.

Since friction is the means employed in shuttle boxes in stopping theshuttle, and since friction is a quantity that varies with such factorsas wear, temperature, and moisture, high shuttle speeds such, forexample, as speeds in excess of sixty feet per second cause inaccuratestopping of the shuttle, with the result that the shuttle is not in thecorrect position to'be startedin the a reverse direction for thesucceeding pass. In

order to obtain even reasonably accurate stopping of the shuttle bymeans of a shuttle box at high shuttle speeds, continuous personalsupervision and adjustment by an operator are necessary.

. Accordingly, a further object of the'invention is the provision of animproved stopping means which will stop the shuttle accurately in thecorrect position andwhich will reduce the attention of an operator to aminimum.

A further object of the invention is the provision of a shuttle stoppingmeans which will stop the shuttle accurately in the correct positionirrespectively of the speed of the shuttle.

so The use of shuttle boxes, picker sticks,.and cooperating mechanism isattended with a great amount of noise. In fact, the noise attending theoperation of looms in a weaving mill is a, veritable din and perhapsexceeds the noise attendingthe Q5 carrying out-of any other industrialoperation.

Accordingly, a further object of this invention is the effecting of asubstantial reduction in the amount of noise attending the operation oflooms. Other objects will become apparent from a reading of theaccompanying specification. 5 In carrying the invention into efiect inone form thereof, means are provided adjacent the warp shed, i. e., theshed formation of warp threads through which the shuttle travels, forproducing a magneticfield, and an armature 10 member is mounted formovement in this magnetic field and is so arranged that it is str'-ck bythe shuttle at the end of the pass. During the Impact of the shuttlewith the armature, the kinetic energy of the shuttle is transferred tothe 18 armature so that the shuttle is brought to rest and the armatureis set in motion. The energy so transferred to the armature isdissipated as a result of the currents produced by movement of thearmature in the magnetic field. go

For a better and more complete understanding of the invention, referenceshould now be had to the following specification and to the accompanyingdrawing of which Fig. 1 is a simple, diagrammatical view in elevation ofan embodiment of 35 the invention, Fig. 2 is a plan view of theembodiment of Fig. 1, and Fig. 3 is a plan view illustratingtheapplication of the invention to both sides of the loom to providestopping the shuttle at each end of the lay. 30

Referring now to the drawing, a shuttle l0 containing a bobbin ofthread, yarn, or other suitable filling material (not shown) is shown atthe lefthand extremity of its path of travel. As is well understood, thepath of travel of the shuttle lies 85 within the shed formed by the warpthreads as a result of the action of the loom harnesses. The warpthreads are omitted from, the drawing since they do not constitute anypart of the present invention. The path, of the shuttle is representeding a strong magnetic field. These means are illustrated as anelectromagnet 12 provided with a core member l2; having poles in and 2cfac ing each other and separated by an air gap which V is crossed by themagnetic flux of'the magnet.

An exciting coil l2d surrounds the core member and is connected to asuitable D. C. source of supply reprsented by the supply line [3. Avariable resistor ll is included in the connections for vary-- a ing theexcitation of the coil I 24 and the magnetic flux of the magnet.

A suitable armature member is mounted in the air gap between the polesof the magnet. This armature member is an induction disc member I5provided with pivots I6 and I I which are journaled for rotation insuitable bearings. The disc is made of a suitable metal such as aluminumor one of the well-known aluminum alloys. The disc I5 is mounted forrotation in the air gap between the poles of the magnet and is providedwith a projection I8 which extends into the path of travel of theshuttle so as to be struck by the shuttle at the end of its flight. Thisprojection is made of rubber or other suitable material and is attachedto the disc I5 by any suitable fastening means (not shown).

The diameter and thickness of the disc I5 are so determined that themoment of inertia of the disc with respect to its axis of rotation issubstantially equal to the moment of inertia of the shuttle at the pointof contact with the projection I8, with respect to the axis of rotationof the disc.

Thus in the case of a shuttle weighing one pound and arranged to strikethe projection I8 at the periphery of the disc, a disc weighing twopounds would have the same moment of inertia with respect to its ownaxis of rotation as that of the one pound shuttle with respect to thisaxis. Assuming the thickness of the aluminum disc as in., the diameterof the disc will be approximately 10 in.

A stop member I9 is provided in the path of the projection I8 so as tobe struck by the projection and thereby to reverse the direction ofrotation of the disc. Suitable means illustrated as a spiral spring areprovided for returning the disc to its initial position.

With the foregoing understanding of the elements and their organizationin the completed device, the operation of the device itself will readilybe understood from the following detailed description.

Assuming the shuttle III to be at rest at the left-hand extremity of theloom as viewed in the figures of the drawing, it is accelerated to ahigh speed, e. g. 60 ft. per second by suitable accelerating means 2|.The shuttle traverses the warp shed at this speed until it reaches theprojection H3 at the opposite end of the shed. The accelerating membersof the accelerating means 22 at the opposite. end of the shed arewithdrawn so that the shuttle passes these accelerating means withoutcoming in contact therewith. The end of the shuttle strikes theprojection I8 of the disc I5 which at'this time is at rest. The kineticenergy of the shuttle is transferred to the disc I5 and the shuttle israpidly decelerated to rest. Since the moment of inertia of the shuttleand disc with respect to the axis of rotation of the disc are preferablyequal, the shuttle comes to an immediate dead stop just as the cuebilliard ball comes to an immediate dead stop when it strikes thestationary ball squarely on a line joining the centers of both balls.Since the accurate stopping of the shuttle I II by transfer of itskinetic energy to the armature l5 depends only upon the relationship ofthe moments of inertia of the shuttle and armature, and since the momentof inertia of a body is independent of its speed, the accurate stoppingof the shuttle in the correct position is independent of its speed.

As a result of the transfer of the kinetic energy of the shuttle to thedisc I 5, the disc is set in rotation and eddy currents are caused tocirculate in the disc as a result of the rotation of the disc throughthe magnetic field between the poles of the magnet I2 and the storedenergy oi the disc is dissipated in the form of heat produced by theseeddy currents.

The stop I9 is preferably positioned so that it will be struck by theprojection [8 before the stored energy of the disc is completelydissipated. As a result of the projection I8 striking the stop I9 thedirection of rotation of the disc will be reversed, and the dissipationof stored energy will continue during the reverse rotation of the disc.The [position of the stop I9 and the strength of excitation of themagnet I2 are so correlated that the stored energy of the disc will becompletely dissipated during the reverse rotation and the spring 20 willcomplete the restoration of the disc to its initial position with theprojection II extending athwart the path of travel of the shuttle.

During the rotation of the disc, the accelerating means 22 willaccelerate the shuttle for the return flight through the shed so thatthe spring 20 can complete the restoration of the disc to its initialposition in which it is left in a reset condition to repeat theoperation described in the foregoing.

The weight of the loaded shuttle varies slightly as the filling iswithdrawn from the bobbin. Thus, if the moment of inertia of the shuttleis greater than the moment of inertia of the disc by the weight of thefilling, the shuttle would tend to pass beyond the point at which itstrikes the projection on the disc. To overcome this, suitable meansillustrated as a spring actuated clamping means 23 are provided forapplying a light friction to stop the shuttle;, in the correct position.

As shown in Fig. 3, similar stopping means 24 identical with thosedescribed in the foregoing are provided for stopping the shuttle at theend of its flight in the reverse direction.

Although in accordance with the provisions of the patent statutes thisinvention is described as embodied in concrete form and the principle ofthe invention has been explained together with the best mode in which itis now contemplated applying that principle, it will be understood thatthe elements described as shown and described are merely illustrativeand that the invention is not limited thereto since alterations andmodifications will readily suggest themselves to persons skilled in theart without departing from the true spirit of this invention or from thescope of the annexed claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

l. Mechanism for stopping a loom shuttle at the end of each passcomprising in combination, an electromagnet arranged adjacent the shedof the warp material, an armature member arranged for rotation in thefield of said electromagnet and positionally arranged to be set inmotion by said shuttle whereby said shuttle gives up its kinetic energyto said armature and is brought rapidly to rest, and said armaturedissipates said transferred energy as a result of its rotation in saidmagnetic field.

2. Mechanism for stopping a loom shuttle at the end of each passcomprising in combination, a magnet arranged adjacent the shed of thewarp near the end of the pass of said shuttle. an armature mounted forrotation in the field of said magnet and provided with a projectionextending into the path of said shuttleto be struck thereby so that saidshuttle gives up its 7 energy to said armature member and comes to animmediate stop and said armature is set in motion and dissipates saidtransferred energy by currents resulting from the movement of saidarmature in said magnetic field.

3. A device for stopping the shuttle of a loom comprising incombination, a magnet mounted adjacent the warp' shed provided withpoles facing each other and separated by an air gap, an armature mountedfor rotation in said air gap and having a projection extending into thepath of said shuttle, said armature and said shuttle havingsubstantially equal moments of inertia with respect to the center ofrotation of said armature so that the kinetic energy of said shuttle isgiven up to said armature and said shuttle brought substantiallyimmediately to a stop as a result of the impact of said shuttle withsaid projection and said transferred energy is dissipated by theproduction of eddy currents in said armature as a result of the rotationof said armature in the field of said magnet.

4. A device for stopping the shuttle of a ioom comprising incombination, a magnet mounted adjacent the path of the shuttle andhaving poles facing each other separated by an air gap, a disc mountedfor rotation in said air gap and arranged to be set in rotation by animpact of said shuttle so that said shuttle gives up a major portion ofits kinetic energy to said disc to stop said shuttle and the energy ofsaid disc is dissipated by eddy currents produced by rotation of saiddisc in the field of said magnet, and a spring for returning said discto its initial position.

5. A device for stopping the shuttle of a loom comprising incombination, a magnet mounted adjacent the warp shed and having polesseparated by an air gap, a disc armature mounted for rotation in saidair gap and arranged to be set in rotation by impact of said shuttlewith said disc so that said shuttle gives up a major portion of itskinetic energy to said disc armature thereby to effect stopping of saidshuttle and said transferred energy is dissipated by eddy currentsproduced by rotation of said disc in the field of said magnet, a stopfor reversing the direction of rotation of said disc armature beforesaid transferred energy is completely dissipated and means for returningsaid disc to its initial position after said transferred energy iscompletely dissipated.

8. A device for stopping the shuttle of a loom comprising incombination, a magnet mounted inproximitytothe warpshed andhaving polesfacing each other and separated by an air gap and a disc armature membermounted for rotation in said air gap and provided with a projectionextending into the path of said shuttle so that saiddisc is set inrotation by impact of said shuttle with said projection, and saidshuttle transfers a substantial portion of its kinetic energy to saiddisc thereby to stop said shuttle, the energy transferred to said discbeing dissipated in the form of heat by eddy currents produced by therotation of said disc in the field of said magnet, a stop arranged inthe path of said projection for reversing the direction-of rotation ofsaid disc prior to complete dissipation of said transferred energythereby to provide for returning said disc toward its initial positionwhile said energy isbeing dissipated, and means for returning said discto said initial position after said energy is completely dissipated, 1

'7. A device for stopping the shuttle of a loom comprisng' incombination, an electromagnet mounted in proximity to the warp shed andhaving poles facing each other and separated by an air gap, a discarmature member mounted to rotate in said air gap and arranged to be setin rotation by impact of said shuttle therewith whereby the kineticenergy of said shuttle is transferred to said disc and said shuttle isbrought to'rest, said transferred energy being dissipated in the form ofheat produced from eddy currents generated in said disc as a result ofthe rotation of said disc in the field of said magnet and 'means forvarying the excitation of said magnet to vary the rate of dissipation ofchange of kinetic energy in said disc to electrical energy.

8. A device for stopping the shuttle of a loom comprising incombination, an electromagnet mounted in proximity to the warp'shed andhaving poles facing each other and separated by an air gap, a discarmature mounted for rotation in said air gap and provided with aprojection extending into the path of said shuttle, said disc armatureand said shuttle having substantially equal moments of inertia withrespect to the axis of rotation of said disc so that said shuttle givesup a substantial portion of its kinetic energy to said disc and isdecelerated as a result of impact with said projection, and the energytransferred to said disc is dissipated as a result of the rotation ofsaid disc in the field of said magnet, and a friction device forabsorbing the residue of the kinetic energy of said shuttle thereby tostop said shuttle in a predetermined P tion.

BENJAMIN W. JONES.

